Fresh produce offers many quality, nutritional, and perceived benefits over cooked or otherwise processed foods. However, fresh foods are perishable products with short shelf lives that undergo senescence, or the natural aging and gradual deterioration process, and they are highly susceptible to pathogens. Perishable products must therefore be maintained in a lower temperature environment to slow this aging process and to retard the growth of spoilage pathogenic organisms. Lowering the temperature leads to increased shelf life and higher quality without cooking or drying the product, and without using chemicals, or extremely high pressures for preservation. The lower the temperature, the more the internal metabolic processes that causes senescence are slowed, or even stopped. However, lowering the temperature to at or below freezing may cause tissue damage to the product so that it is no longer in its desired fresh or natural state. Freezing may damage the texture and negatively affect product integrity and nutritional profile.
Current methods of cooling perishable products use several different techniques these include, for example, immersion, forced air cooling, hydro-cooling, and vacuum cooling.
Forced air cooling, whereby air is drawn across the product, may take several hours to cool the products. Thus, it is less effective at slowing senescence. Furthermore, the product packaging requires sufficient venting for core product temperatures to be uniformly reduced to optimum levels.
Hydro-cooling utilizes cold water to drench the product. This process takes less time to cool the products and is more efficient than forced air cooling but is not appropriate for all perishable products, especially where direct water contact has a negative impact on product quality making it less than the ideal solution for many products.
Vacuum cooling whereby air is withdrawn from a sealed chamber lowering the boiling point, facilitates evaporative cooling and may cause rapid cooling of the product (additional refrigeration is often added to further speed this process). This process is relatively fast but takes a very large amount of energy to cool the products, and is not appropriate for cooling many perishables that cannot withstand the negative pressure experienced during this process.
Although all of these various cooling methods (including other commercial cooling methods not described) have a use for some products and some circumstances, all these processes fail in their ability to further benefit the product and/or further slow the metabolic processes. In addition, at a point where ice crystals or product freezing occurs the potential benefits from cooling in all of these processes are replaced by negative impact of product damage. Once the product's cells are damaged from chilling injury, or more typically freezing and no longer frozen, these products are even more susceptible to degradation, spoilage, and pathogenic organisms.
The thermal transfer of heat energy from perishable products and organisms effectively “decreases” the metabolic rate/respiration slowing biological processes and senescence, in the case of produce this decrease generally occurs in a manner proportional to the Q10 decrease in temperature. As the products, spoilage and/or other living organisms' temperature approaches freezing, biological processes slow but more energy is required for each proportional decrease in temperature. Once a product or organism reaches its freezing point, the negative effects from a further decrease in temperature can only be managed by creating a targeted and controlled disruption/prevention of ice crystals and undesirable reactions that lead to cellular damage. The use of targeted energy transfer to a product within a controlled environment can reduce the chance for damage due to freezing by using waves of certain frequency prior to, during, and immediately after a product is cooled to or below its normal freezing temperature. The result is a product whose metabolic processes have been slowed or nearly stopped for a time and when this technique is combined with other carefully applied good handling practices it will allow that product to have a longer shelf-life than other fresh or perishable products that were not supercooled.
Therefore, there is a need in the art for systems and methods of supercooling perishable products that overcome the foregoing and other drawbacks of the prior art.